I have my entire house configured to distribute video sources through the cable line. I have a lot of knowledge on the subject because I've been running this setup for about 18 months, so I just wanted to share some information with the community that has helped me so much over the past month.
Basically, I have one main setup in my living room with all of my components, (Mythtv, DVD, Tivo, Digital Cable box etc). The other TVs across the house can all watch my video sources by changing to a specific channel.
I use the Channel Plus 3025 Whole House Video Distribution box to do this. It can take two video/audio sources (via RCA jacks) and modulate them onto two different cable channels. For instance, if I set my MythTV output to composite (RCA style) video and run an RCA jack Y-cable out of my soundcard...I can run those outputs in the Channel Plus. I can then set channel 92 (or any high channel) to be my MythTV. I run the five outputted RF cables from the Channel Plus to the other TVs in my house. Then I just turn to channel 92 from any TV in the house and I can watch my MythTV.
The video quality is as good as RF can get, but remember, it is still RF cable. My living room setup is nice, but the other TVs in the house are just 27 inch or smaller, with no fancy speakers or anything...so the video quality is pretty decent. I wouldn't suggest this setup to output to big screens or anything. Basically, it will distribute an RF signal that is very close to the quality of the input signal. (My eyes can't tell the difference on a 25 inch TV.)
Anyway, overall I'm very happy with this setup and it is much cheaper than running multiple frontends. (Keep in mind that everyone watching the MythTV has to watch the same show. This is fine for 2 people in a house with many rooms and TVs, but may not be as useful for a family of 5 who want to watch different shows simultaneously.) Also, note that the other TVs in the house still have full access to the regular analog cable channels...that doesn't change in this model.
This is where I purchased the Channel Plus from because they had the best price:
http://www.etronics.com/product.asp?stk_code=cha3025
If you search, there are many different Channel Plus products that support more input sources and better video quality (s-video) if you want to spend the money, but I'm happy with my two input source RF box. I also have a basic RCA switchbox in front of it, so that I can hook up additional sources.
The other piece to the puzzle is remote repeaters. Keep in mind that the ChannelPlus will distribute video and audio, but you won't have any remote control capabilities. For that, you need remote repeaters, which are very easy to install and use. Buy a "receiver" and aim it at your video components (MythTv, DVD, etc.). Then buy a "transmitter" for every "other" TV in the house. When you aim a remote at a transmitter, the signal gets converted to RF, sent through the air to the receiver, and then resent via IR from the receiver to your components...thus allowing control from any room.
I use 5 Powermid transmitters in my house and one receiver. You can get them here:
http://www.crutchfield.com/S-bk0XugjsGQ ... T&g=194550
Last, but not least...if you don't want to have to carry your one and only remote all over the house, you should get some extra universal remotes. One For All makes excellent remotes for great prices.
http://www.ofausa.com/list_remotes.php? ... eam%20Line
I have a URC-6131 in every room of the house, which controls all of my video sources. You can usually find these for about $20, which makes them a great value. (I have mine JP1 modified for additional customization, but that's another story.)
Anyway, I just wanted to give everyone a little direction in case they ever wanted to Myth-ify their entire house without setting up multiple frontends. If I left anything out, or if you have any questions on the subject, feel free to reply to the thread.